Field of the Invention
The present invention relates to an organic thin film transistor, an organic semiconductor thin film, and an organic semiconductor material. Specifically, the invention relates to an organic semiconductor material for a non-light-emitting organic semiconductor device containing a compound having a benzobisbenzofuran derivative structure (which may be hereinafter referred to as a BBBF derivative structure), an organic semiconductor thin film containing the material, and an organic thin film transistor using the thin film.
Background Art
A device using an organic semiconductor material is expected to have various advantages as compared to a device using an ordinary inorganic semiconductor material, such as silicon, and thus is receiving a high level of interest. Examples of the device using an organic semiconductor material include a photoelectric conversion device using an organic semiconductor material as a photoelectric conversion material, such as an organic thin film solar cell and a solid-state imaging device, and a non-light-emitting organic transistor. A device using an organic semiconductor material has a possibility of producing a large area device at a low temperature and low cost, as compared to a device using an inorganic semiconductor material. Furthermore, the material characteristics may be easily changed by changing the molecular structure thereof, thereby providing a wide range of varieties of the materials, and thus functions and devices that are not achieved with an inorganic semiconductor material may be realized.
For example, Patent Reference 1 describes the compound represented by the following general formula having as a partial structure a condensed ring containing five rings including aromatic heterocyclic rings (in which ring A and ring B each represent a benzene ring or a particular 5-membered aromatic heterocyclic ring; T1 and T2 each represent sulfur, selenium, tellurium, oxygen, phosphorus, boron or aluminum; R1 to R4 each represent a hydrogen atom, an alkyl group, or the like; and l and m each represent 0 or 1). Patent Reference 1 describes that the compound represented by the following general formula may form a semiconductor active layer and may be an organic semiconductor material that is capable of forming the film by coating. In the literature, the compound is used as an organic semiconductor material and forms an organic thin film, but the transistor characteristics and the like thereof are not described.

Patent Reference 2 and Non-patent Reference 1 describe the use of a polycyclic condensed ring compound containing an aromatic heterocyclic ring in an organic transistor. Patent Reference 2 suggests the application of an organic compound having a benzobisbenzofuran (which may be hereinafter referred to as BBBF) skeleton to an organic thin film transistor, but does not describe an example that show the purpose as an organic transistor and the transistor characteristics. Non-patent Reference 1 suggests that some of compounds having a BBBF skeleton appear promising as a material for an organic electroluminescent transistor. However, the organic electroluminescent transistor only has transistor characteristics that are in an elementary level and fails to achieve a practical level due to the low mobility.
Patent Reference 3 describes an organic compound having a benzobisnaphthofuran (which may be hereinafter referred to as BBNF) skeleton, in addition to an organic compound having a BBBF skeleton, and describes that the organic compound is useful as a material for an organic EL device. Patent Reference 3 only describes the usefulness as a material for an organic EL device, but does not describe or suggest the application thereof to an organic thin film transistor.